The present invention relates to endless belt conveyors for transferring granular material such as seed or grain and of the general type disclosed in U.S. Pat. Nos. 3,212,628, 5,052,545 and 6,675,958, the latter Patent having a disclosure herein incorporated by reference. In such a conveyor, an endless flexible belt extends around rollers located at opposite end portions of the conveyor, and an upper run of the endless belt extends through a tubular or cylindrical housing. The housing has an inner diameter smaller than the width of the flexible belt so that the upper run of the belt curves upwardly within the tubular housing to form a continuously moving trough for conveying the material.
A common problem with such a conveyor when transferring seed or grain is caused by belt misalignment on the rollers and within the tubular housing. This causes one side of the curved belt within the housing to move or shift upwardly above the other side with the result that some of the seed falls under the belt. This results in some of the seeds being crushed and collecting on the rollers to create further misalignment of the belt and also loss of seed or seed damage. It is then necessary to stop the conveyor, clean the rollers and realign the belt on the rollers.
In endless belt conveyors where the upper run of the belt remains flat when transferring material, it is known to maintain the belt in alignment with the end rollers and prevent lateral shifting of the belt by the use of some form of guide rib or ribs attached to the inner surface of the endless conveyor belt. The guide rib is directed into grooves formed within the end rollers for the belt, for example, as disclosed in U.S. Pat. Nos. 3,186,536 and 7,428,858. In such conveyors, the flat upper run of the conveyor belt is commonly supported by flat surfaces or closely spaced rollers having grooves for receiving the guide rib and to prevent friction wear of the guide rib by the weight of the material being transferred.